/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)malloc.c	5.11 (Berkeley) 2/23/91";
#endif				/* LIBC_SCCS and not lint */

/*
 * malloc.c (Caltech) 2/21/82
 * Chris Kingsley, kingsley@cit-20.
 *
 * This is a very fast storage allocator.  It allocates blocks of a small
 * number of different sizes, and keeps free lists of each size.  Blocks that
 * don't exactly fit are passed up to the next larger size.  In this
 * implementation, the available sizes are 2^n-4 (or 2^n-10) bytes long.
 * This is designed for use in a virtual memory environment.
 */

#define IN_MALLOC_WRAPPER
#define NO_OPCODES
#include "std.h"
#include "main.h"

#undef NULL
#define	NULL 0

#ifdef _SEQUENT_
typedef unsigned char u_char;
typedef unsigned short u_short;
typedef unsigned int u_int;

#endif

/*
 * The overhead on a block is at least 4 bytes.  When free, this space
 * contains a pointer to the next free block, and the bottom two bits must
 * be zero.  When in use, the first byte is set to MAGIC, and the second
 * byte is the size index.  The remaining bytes are for alignment.
 * If range checking is enabled then a second word holds the size of the
 * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
 * The order of elements is critical: ov_magic must overlay the low order
 * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
 */
union overhead
{
	union overhead *ov_next; /* when free */
	struct
	{
		u_char ovu_magic; /* magic number */
		u_char ovu_index; /* bucket # */
#ifdef RCHECK
	u_short ovu_rmagic; /* range magic number */
	u_int ovu_size; /* actual block size */
#endif
	} ovu;
#define	ov_magic	ovu.ovu_magic
#define	ov_index	ovu.ovu_index
#define	ov_rmagic	ovu.ovu_rmagic
#define	ov_size		ovu.ovu_size
};

#define	MAGIC       0xef	/* magic # on accounting info */
#define RMAGIC		0x5555	/* magic # on range info */

#ifdef RCHECK
#define	RSLOP		sizeof (u_short)
#else
#define	RSLOP		0
#endif

/*
 * nextf[i] is the pointer to the next free block of size 2^(i+3).  The
 * smallest allocatable block is 8 bytes.  The overhead information
 * precedes the data area returned to the user.
 */
#define	NBUCKETS 30
static union overhead *nextf[NBUCKETS];

static int pagesz; /* page size */
static int pagebucket; /* page size bucket */

static void morecore(int);
static int findbucket(union overhead *, int);

#ifdef DO_MSTATS
/*
 * nmalloc[i] is the difference between the number of mallocs and frees
 * for a given block size.
 */
static u_int nmalloc[NBUCKETS];

#endif

#if defined(DEBUG) || defined(RCHECK)
#ifdef __STDC__
#define	ASSERT(p)   if (!(p)) botch(#p)
#else
#define ASSERT(p)   if (!(p)) botch("?")
#endif
static int botch(char * s)
{
	debug_message("\r\nassertion botched: %s\r\n", s);
	(void) fflush(stderr); /* just in case user buffered it */
	abort();
	return 0;
}
#else
#define	ASSERT(p)
#endif

#ifdef malloc
/* linux */
#undef malloc
#endif
void *bsdmalloc_malloc(size_t nbytes)
{
	register union overhead *op;
	register int bucket, n;
	register unsigned amt;

	/*
	 * First time malloc is called, setup page size and align break pointer
	 * so all data will be page aligned.
	 */
	if (pagesz == 0)
	{
#ifdef MEMPAGESIZE
		pagesz = n = MEMPAGESIZE;
#else
		pagesz = n = getpagesize();
#endif
		op = (union overhead *) sbrk(0);
		n = n - sizeof(*op) - ((int) op & (n - 1));
		if (n < 0)
			n += pagesz;
		if (n)
		{
			if ((char *) sbrk(n) == (char *) -1)
				return (NULL);
		}
		bucket = 0;
		amt = 8;
		while (pagesz > amt)
		{
			amt <<= 1;
			bucket++;
		}
		pagebucket = bucket;
	}
	/*
	 * Convert amount of memory requested into closest block size stored in
	 * hash buckets which satisfies request. Account for space used per block
	 * for accounting.
	 */
	if (nbytes <= (n = pagesz - sizeof(*op) - RSLOP))
	{
#ifndef RCHECK
		amt = 8; /* size of first bucket */
		bucket = 0;
#else
		amt = 16; /* size of first bucket */
		bucket = 1;
#endif
		n = -((int) sizeof(*op) + RSLOP);
	}
	else
	{
		amt = pagesz;
		bucket = pagebucket;
	}
	while (nbytes > amt + n)
	{
		amt <<= 1;
		if (amt == 0)
			return (NULL);
		bucket++;
	}
	/*
	 * If nothing in hash bucket right now, request more memory from the
	 * system.
	 */
	if ((op = nextf[bucket]) == NULL)
	{
		morecore(bucket);
		if ((op = nextf[bucket]) == NULL
		)
			return (NULL);
	}
	/* remove from linked list */
	nextf[bucket] = op->ov_next;
	op->ov_magic = MAGIC;
	op->ov_index = bucket;
#ifdef DO_MSTATS
	nmalloc[bucket]++;
#endif
#ifdef RCHECK
	/*
	 * Record allocated size of block and bound space with magic numbers.
	 */
	op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
	op->ov_rmagic = RMAGIC;
	*(u_short *) ((caddr_t) (op + 1) + op->ov_size) = RMAGIC;
#endif
	return ((char *) (op + 1));
}

/*
 * Allocate more memory to the indicated bucket.
 */
static void morecore(int bucket)
{
	register union overhead *op;
	register int sz; /* size of desired block */
	int amt; /* amount to allocate */
	int nblks; /* how many blocks we get */

	/*
	 * sbrk_size <= 0 only for big, FLUFFY, requests (about 2^30 bytes on a
	 * VAX, I think) or for a negative arg.
	 */
	sz = 1 << (bucket + 3);
#ifdef DEBUG
	ASSERT(sz > 0);
#else
	if (sz <= 0)
		return;
#endif
	if (sz < pagesz)
	{
		amt = pagesz;
		nblks = amt / sz;
	}
	else
	{
		amt = sz + pagesz;
		nblks = 1;
	}
	op = (union overhead *) sbrk(amt);
	/* no more room! */
	if ((int) op == -1)
		return;
	/*
	 * Add new memory allocated to that on free list for this hash bucket.
	 */
	nextf[bucket] = op;
	while (--nblks > 0)
	{
		op->ov_next = (union overhead *) ((caddr_t) op + sz);
		op = (union overhead *) ((caddr_t) op + sz);
	}
}

INLINE void bsdmalloc_free(void * cp)
{
	register int size;
	register union overhead *op;

	if (cp == NULL
	)
		return;
	op = (union overhead *) ((caddr_t) cp - sizeof(union overhead));
#ifdef DEBUG
	ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */
#else
	if (op->ov_magic != MAGIC
	)
		return; /* sanity */
#endif
#ifdef RCHECK
	ASSERT(op->ov_rmagic == RMAGIC);
	ASSERT(*(u_short *) ((caddr_t) (op + 1) + op->ov_size) == RMAGIC);
#endif
	size = op->ov_index;
	ASSERT(size < NBUCKETS);
	op->ov_next = nextf[size]; /* also clobbers ov_magic */
	nextf[size] = op;
#ifdef DO_MSTATS
	nmalloc[size]--;
#endif
}

/*
 * When a program attempts "storage compaction" as mentioned in the
 * old malloc man page, it realloc's an already freed block.  Usually
 * this is the last block it freed; occasionally it might be farther
 * back.  We have to search all the free lists for the block in order
 * to determine its bucket: 1st we make one pass thru the lists
 * checking only the first block in each; if that fails we search
 * ``realloc_srchlen'' blocks in each list for a match (the variable
 * is extern so the caller can modify it).  If that fails we just copy
 * however many bytes was given to realloc() and hope it's not huge.
 */
int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */

void *bsdmalloc_realloc(void * cp, size_t nbytes)
{
	register u_int onb;
	register int i;
	union overhead *op;
	char *res;
	int was_alloced = 0;

	if (cp == NULL
	)
		return (bsdmalloc_malloc(nbytes));
	op = (union overhead *) ((caddr_t) cp - sizeof(union overhead));
	if (op->ov_magic == MAGIC)
	{
		was_alloced++;
		i = op->ov_index;
	}
	else
	{
		/*
		 * Already free, doing "compaction".
		 * 
		 * Search for the old block of memory on the free list.  First, check
		 * the most common case (last element free'd), then (this failing)
		 * the last ``realloc_srchlen'' items free'd. If all lookups fail,
		 * then assume the size of the memory block being realloc'd is the
		 * largest possible (so that all "nbytes" of new memory are copied
		 * into).  Note that this could cause a memory fault if the old area
		 * was tiny, and the moon is gibbous.  However, that is very
		 * unlikely.
		 */
		if ((i = findbucket(op, 1)) < 0
		        && (i = findbucket(op, realloc_srchlen)) < 0)
			i = NBUCKETS;
	}
	onb = 1 << (i + 3);
	if (onb < pagesz)
		onb -= sizeof(*op) + RSLOP;
	else
		onb += pagesz - sizeof(*op) - RSLOP;
	/* avoid the copy if same size block */
	if (was_alloced)
	{
		if (i)
		{
			i = 1 << (i + 2);
			if (i < pagesz)
				i -= sizeof(*op) + RSLOP;
			else
				i += pagesz - sizeof(*op) - RSLOP;
		}
		if (nbytes <= onb && nbytes > i)
		{
#ifdef RCHECK
			op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
			*(u_short *) ((caddr_t) (op + 1) + op->ov_size) = RMAGIC;
#endif
			return (cp);
		}
		else
			bsdmalloc_free(cp);
	}
	if ((res = bsdmalloc_malloc(nbytes)) == NULL
	)
		return (NULL);
	if (cp != res) /* common optimization if "compacting" */
		memcpy(res, cp, (nbytes < onb) ? nbytes : onb);
	return (res);
}

/*
 * Search ``srchlen'' elements of each free list for a block whose
 * header starts at ``freep''.  If srchlen is -1 search the whole list.
 * Return bucket number, or -1 if not found.
 */
static int findbucket(union overhead * freep, int srchlen)
{
	register union overhead *p;
	register int i, j;

	for (i = 0; i < NBUCKETS; i++)
	{
		j = 0;
		for (p = nextf[i]; p && j != srchlen; p = p->ov_next)
		{
			if (p == freep)
				return (i);
			j++;
		}
	}
	return (-1);
}

#ifdef DO_MSTATS
/*
 * mstats - print out statistics about malloc
 *
 * Prints two lines of numbers, one showing the length of the free list
 * for each size category, the second showing the number of mallocs -
 * frees for each size category.
 */
void
show_mstats(outbuffer_t * ob, char * s)
{
	register int i, j;
	register union overhead *p;
	int totfree = 0, totused = 0;

	outbuf_addv(ob, "Memory allocation statistics %s\nfree:\t", s);
	for (i = 0; i < NBUCKETS; i++)
	{
		for (j = 0, p = nextf[i]; p; p = p->ov_next, j++);
		outbuf_addv(ob, " %d", j);
		totfree += j * (1 << (i + 3));
	}
	outbuf_add(ob, "\nused:\t");
	for (i = 0; i < NBUCKETS; i++)
	{
		outbuf_addv(ob, " %d", nmalloc[i]);
		totused += nmalloc[i] * (1 << (i + 3));
	}
	outbuf_addv(ob, "\n\tTotal in use: %d, total free: %d\n",
			totused, totfree);
}
#endif

/* calloc was originally in its own source file */
#ifdef calloc
/* linux */
#undef calloc
#endif
INLINE void *bsdmalloc_calloc(size_t num, register size_t size)
{
	register void *p;

	size *= num;
	if ((p = bsdmalloc_malloc(size)))
		memset(p, 0, size);
	return (p);
}
